JPS6036977B2 - Lock prevention control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention provides an inflow valve and an outflow valve for electrically controlling the brake pressure, respectively, and a rotational speed generator for generating a direct current voltage proportional to the rotational speed of at least one vehicle wheel. A method for controlling an anti-lock control device comprising a circuit arrangement for generating first and second derivatives of wheel speed with respect to time, and a threshold switch for controlling said valve via a logically coupled circuit. .

In the lock prevention control method, firstly, it is necessary to react as quickly as possible to changes in wheel acceleration, and secondly, the dark value of the acceleration at which the opening/closing operation of the valve is started must be adapted to the road condition.

It has already been proposed to provide a monostable multipipulator that can measure the time required for reacceleration of the wheels to meet the second requirement. In short, the monostable multivibrator makes it possible to distinguish between two different values of the derivative of the wheel acceleration with respect to time.

This makes it possible to distinguish between two different road conditions, since the time required for reacceleration of the vehicle wheels is determined primarily by the coefficient of friction between the wheels and the road. A correlation value is usually set to distinguish between a dry, non-slip road and a wet, somewhat slippery road.

It is even more preferable to be able to distinguish between at least three different road conditions, including not only the two road conditions above, but also an icy condition that is extremely slippery. Therefore, the object of the present invention is to improve the above-mentioned lock prevention control method as follows.
The objective is to improve the ability to automatically adapt to different road conditions.

To solve this problem, according to the present invention, in the lock prevention control method, a signal corresponding to the second derivative of the wheel speed with respect to time is detected, and the first derivative is detected following a decrease in brake pressure. If the vehicle is traveling on a slip-resistant road, and the signal corresponding to the second derivative exceeds a predetermined first function value, the brake pressure is held constant and the brake pressure is increased. In the time phase following the constant holding time phase, if the signal corresponding to the second derivative exceeds a predetermined second threshold value that is larger than the first threshold value, the brake pressure is continuously increased and when the signal falls below the second derivative value. The brake pressure is increased stepwise under clock control at a slope less than the continuous increase slope, and b. When the vehicle is traveling on a somewhat slippery road, the signal corresponding to the second derivative is increased at a predetermined level. 1st
If the brake pressure exceeds the dark value, the brake pressure is held constant, and in a time phase following the brake pressure constant holding time phase, a predetermined second value is set in which the signal corresponding to the second derivative is greater than the first dark value. If the threshold value is not exceeded, the brake pressure is increased in stages under clock control at a slope slower than the continuous increase slope;
c. When the vehicle is traveling on an extremely slippery road, the brakes are not activated if the signal corresponding to the second derivative does not exceed a predetermined first threshold value and a predetermined second threshold value greater than the first threshold value. There is a groove in which the brake pressure is reduced following the brake pressure reduction.

In that case, the first and second dark values are set to positive values, so that the switch with both threshold values responds when the first derivative of the vehicle wheel speed increases.

As the first derivative of the vehicle wheel speed increases, depending on the road condition, either two dark value switches, just one value switch, or none at all respond, resulting in three different road conditions. can be distinguished. The invention will now be described with reference to the illustrated embodiments.

A line 180 shown in FIG. 1 shows the time course of the speed V of a vehicle braking on a road where the coefficient of friction changes during braking. It is then assumed that the coefficient of friction is initially large and then becomes small. Correspondingly, the velocity V first decreases relatively sharply and then more gradually. curve 181
indicates the time course of the wheel circumferential speed r.

In that case r is the radius of the vehicle wheel, which is the angular velocity. In this case, assuming that the driver applies full braking, the anti-lock control device periodically raises and lowers the brake pressure. curve 1
Reference numerals 82 and 184 indicate the first or second derivatives of the wheel circumferential speed with respect to time.

As can be seen from curves 182 and 184, on slippery roads more time is required to bring the wheels from significantly greater deceleration values to positive acceleration values. This is because the pressure in the brake pipe can only be reduced at a predetermined and limited rate by the anti-lock control device. The braking moment is therefore also reduced only at limited speeds. Therefore, wheel acceleration curve 18
The maximum value and period in the waveform of 2 are measures for the coefficient of friction between the wheels and the road. The magnitude of this rate of change in curve 182 is shown in curve 184. curve 18
4, a slippery road results in a smaller maximum value than a dry road. If the brake pressure is reduced over a sufficiently long period of time, large positive wheel accelerations r· can be obtained even on slippery roads.

The maximum value of the wheel acceleration r is only slightly smaller on a slippery road than on a dry road (
(see curve 182). In contrast, the maximum value of the second derivative of the wheel peripheral speed on a slippery road is much lower and can therefore be used as a measure for the road condition or the coefficient of friction. In FIGS. 2 and 3, the inverting input side or the inverting output side of the gate is indicated by black dots. In the following description, the usual L and 0 signals in digital circuit technology will be used. When the output side of one stage is set to a positive potential, an L signal is sent out.

Conversely, if the output side is placed at ground potential, a ○ signal is sent out. The anti-lock control device includes a braking device that includes inflow and outflow valves for the pressure medium.

A first magnet coil 26 is provided for operating the inlet valve;
A second magnet coil is used to operate the outflow valve. When no current flows through the magnet coil, the inlet valve is open and the outlet valve is closed, so that only a pressure medium connection between the main brake cylinder and the wheel brake cylinder is formed. Therefore, as soon as the brake pedal is operated, the brake pressure rapidly increases. Simply energizing only the first magnet coil 26 closes the inflow valve, while the outflow valve also remains closed.

The pressure p in the brake line (hereinafter simply referred to as brake pressure) is then kept constant. Additionally, a second
When the magnet coil 27 is excited, the outflow valve is opened and the brake pressure p is reduced. Figure 2 shows both magnet coils 26, 27.
1 shows a first embodiment of a lock prevention control device used for controlling the lock prevention control device.

Input terminal 393 is used for connecting a rotational speed generator (not shown). Speed generators of this type are known in anti-lock control systems. At its output, this rotational speed generator delivers an output DC voltage (which may be filtered) whose magnitude is proportional to the circumferential speed r of the vehicle wheels. A first differentiator 330 is connected to the input terminal 393, and two low-pass filters 332 and 333 are connected to the first differentiator 3301. The first low-pass filter 332 advantageously has a 1 narrow Z upper cutoff frequency;
As a result, a second
A well-filtered output signal is delivered by the low-pass filter 333. If the output signal of the first differentiator 330 changes abruptly, the output signal of the first low-pass filter 332 will correspondingly also be significantly delayed compared to the output signal of the second low-pass filter 333. . A first threshold switch 341 and a second differentiator 335 are connected to the output side of the first low-pass filter 332.

A second value switch 342 and a fifth value switch 340 are connected to the output side of the second low-pass filter 333. The input sides of a third dark value switch 343 and a fourth threshold value switch 344 are connected to the output side of the second differentiator 335. One input side of the speed comparison circuit 347 is input terminal 3.
93, and the other input side is connected to a terminal 394. A DC voltage proportional to the vehicle speed v' is applied to the terminal 394. An L signal is sent from the output side of the speed comparison circuit 347 as soon as an excessively large difference occurs between the vehicle speed v and the wheel circumferential speed.

The outputs of all the function switches 341-347 indicate what signals they will send if they do not respond. The switching values of the individual function switches are indicated by bo~& and v. 1st and 2nd value switch 3
The outputs of 41, 342 are connected to the two inputs of an AND gate 361, the output of which is connected via an OR gate 367 to the set input S of the first memory 351.

The output sides of the fourth threshold value switch 344 and the speed comparison circuit 347 are connected to an AND gate 362. The output sides of the second dark value switch 342 and the AND gate 362 are connected to an OR gate 371, and the output side of this OR gate is connected to the reset input side R of the first memory 351.
The output side of the first memory 351 is connected to one input side of the AND gate 365, to the set input S of the second memory 352, and to one input side of the delay stage 356.

The reset input R of the second memory 352 is connected to a terminal 395, which is connected to the brake light switch of the vehicle. Further, the output side of the second memory 352 is connected to the second input side of the AND gate 365. The output side of the AND gate 365 is used for controlling the second magnet coil 27, ie for controlling the outflow valve.
The output of the delay stage 356 is connected to the reset input S of the third memory 353.

The output side of the third threshold switch 343 is connected to the reset input side R of the third storage device 353. Third storage device 35
3 and the output side of the speed comparison circuit 347 is the AND gate 3.
66 input side, and the output side of this AND gate is connected to the second input side of OR gate 367. The input side of the OR gate 363 is connected in parallel to the input side of the AND gate 366 . The output side of the OR gate 363 is connected to the threshold value adjustment input sides of the first and second dark value switches 341 and 342. Furthermore, unstable multipipulator 3
The cutoff input side E of 65 is connected to the output side of the third threshold switch 343.

Astable multipipulator 355 and second storage 35
The output side of 2 is connected to the input side of AND gate 364. Furthermore, the first magnet coil 26 has an OR gate 372.
is connected to the previous calendar. The four input sides of the OR gate 372 are connected to an AND gate 365, a fifth dark value switch 340, an AND gate 364, and a speed comparison circuit 347. FIG. 5 shows a diagram for explaining the operation of the first embodiment shown in FIG.

Two curves 582 and 584 show the time course of the first and second derivatives of the wheel speed r· with respect to time.

In that case three control cycles are shown, in which case:
It is assumed that the road becomes increasingly slippery during braking. In other respects the curve course is curve 182 in FIG.
, 184 is the same. The next pulse diaphragms 540-572 show the output voltages of the following stages in this order: the fifth step value switch 340 and the first step value switch 341.
The output voltages from the second dark value switch 342, the third value switch 343, the fourth value switch 344, the first memory 351, the third memory 353, the AND gate 365, and the OR gate 352 are shown.

Furthermore, 583 shows a curve of the brake pressure p over time. The operation of the first embodiment shown in FIG. 2 will now be described in detail with reference to FIG.

In that case, to make it easier to understand, the filter passing through both low castles is 332.
, 333 are assumed to have the same delay time. In fact, if the cut-off frequencies are configured to be different, both filters 332 and 33
Although a phase shift occurs in the output signal of No. 3, the time course of the brake pressure p does not change by a relatively small amount and is therefore illustrated for ease of understanding. Further, in the following description, earth acceleration g of approximately low/s2 will be used as a reference value for wheel acceleration. In the embodiment, the fifth threshold switch has a wide switching threshold, and the first switching switch has a switching threshold b. -3. On the fin, switch the second dark value switch -
It is set at 1g. After setting the third storage device 353, the first and second function value switches 341, 34 are connected via the dark value adjustment input side.
The switching function value of 2 is shifted to - or 10 degrees. The input signals of the third and fourth function value switches 343 and 344 are changes in wheel acceleration.

In the first embodiment, the dark value of wide is set to 40 female/s, and the dream value of b4 is set to 20 cough/s. The friction value of 40 f/s is only in the following cases, i.e., the friction coefficient between the wheels and the road is 0.6.
Can only be achieved if greater than The second dark value of 200 g/s is set when the peak is 0.3 to 0.6. When the road surface is even more slippery, the dark value switch 343 is no longer activated.
None of the 344 responded. In that case, the first storage device 35
1 is reset by the second threshold switch 342. At the beginning of the braking process, the brake pressure p rises sharply, since the brake pedal is actuated more and more strongly.

This pressure increase is shown by curve 583 in FIG. Correspondingly, the wheel deceleration increases and finally exceeds the negative threshold value of the fifth dark value switch 340. At this time, the fifth threshold value switch 340 sends out an L signal, and this L signal excites the first magnet coil 26 via the OR gate 372, thereby closing the inflow valve. Correspondingly, the brake pressure p is kept constant. Nevertheless, the wheel is further decelerated, and as soon as the dark value b of -3.5g is exceeded, the first threshold value switch 341 also sends out an L signal.

At the same time, the threshold value b2 of -1g has already been exceeded, and therefore the second function value switch 342 sends out the o signal, so that an L signal now appears on the output side of the AND gate 361. This L signal causes the first memory 3 to pass through the OR gate 367.
51 is set. Therefore, the first memory 351 sends an L signal to its output side and operates the second magnet coil 27 via the AND gate 365. As a result, the outflow valve is opened and the brake pressure p is immediately reduced.

The L signal, which must also be applied to the second input of the AND gate 365 in order to be able to excite the second magnet coil 27, appears as follows:
At the same time as 51, the second memory 352 is also set. The L signal is applied to the reset input side R of the second memory unit 352 only when the foot is removed from the brake pedal again and the brake light goes out.

Therefore, the second storage device 352 will be left out of consideration in the following description. Further, the first memory 351 causes the delay stage 356 to
The set input side of the third memory 353 is controlled via the .

The delay stage 356 is configured as a monostable multipipulator, and is configured such that when an L signal appears on the output side of the first memory 351, an L signal also appears on the output side of the delay stage 356. has been done. As a result, the third memory 3
53 is set, and an L signal is similarly sent out from its output side. As a result, the switching threshold values q and Q are shifted via the OR gate 363 as described above. Due to the steep pressure drop, the braking torque becomes smaller and smaller, so that the wheel deceleration increases only slightly. Curve 582 passes through its minimum value; the wheel deceleration then approaches zero, and again a positive wheel acceleration r. Curve 584 passes through a negative half-wave during the first phase of increased wheel deceleration. Curve 584 passes through zero when wheel deceleration r. passes through its maximum value. When the wheel deceleration moves in the positive direction, the second of the deceleration with respect to time
The second derivative, curve 584, moves to the positive half-wave. It is assumed that at the onset of flaking the road is still dry or slippery and has a coefficient of friction greater than 0.6.

Therefore, during the first positive half-wave of curve 584, both function value switches 343, 344 respond. As soon as the rate of change in wheel acceleration r.w exceeds the 20-bit value b4, the fourth threshold value switch 344 sends out an L signal. At the same time, on the premise that the speed comparison circuit 347 does not respond yet and therefore sends out the ○ signal, the L signal on the output side of the fourth function value switch 344 is transmitted to the first memory 3 via the OR gate 371.
51 is reset. Therefore, the second magnet coil 27
is no longer energized and the outflow valve is closed again.

Therefore, in response to the fourth threshold value switch 344, a phase in which the brake pressure p is kept constant is started.
After a while after the 4th threshold switch, the 3rd threshold switch 3
43 responds. Upon the transition of the L signal on the output side of the third threshold switch 343, the third memory 353 is first cut off. However, it still has no effect on brake pressure. An unstable multipipulator has approximately unity at its output side.
The signal is configured to switch from the O signal to the L signal at a frequency of 00Hz. This multi-pipe plate is shut off by the L signal on its cut-off input side E, and at this time, the brake pressure p is kept constant and a continuous signal is sent to the output side. 26).

This occurs when the output signal of the fifth threshold switch 340 returns to zero. Now, while the third value switch 343 is still sending out the L signal, the brake pressure can again rise sharply. When curve 584 again falls below the 400 g/s threshold, this means that the wheel acceleration r· increases only slightly. Therefore, in order to avoid an excessively large control amplitude of the brake pressure p, the steep pressure rise is interrupted, and when the threshold value of the third threshold value switch 343 is no longer reached, the unstable multipipulator 355 is no longer in the cut-off state; The output pulse clocks magnet coil 26 through OR gate 372, which controls the inflow valve. Therefore, the brake pressure only increases slowly. During the slow pressure rise, the wheel acceleration passes through 0 again and wheel deceleration begins. When the threshold value is reached, the fifth threshold value switch 340 responds again, the first magnet coil 26 is energized via the OR gate 372, and the inflow valve is closed. The subsequent constant holding phase of the brake pressure p also lasts for a short time and is limited by the response of the first threshold value switch 341. The subsequent pressure reduction phases are started and ended in the same manner as in the first control cycle.
Upon response of the fourth dark value switch 344, the outflow valve is closed again, so that the pressure remains constant until the curve 582 crosses the barrier again.

Up to this point, the second control cycle proceeds in exactly the same way as the first control cycle. However, in the second control cycle, it is assumed that the road is somewhat slippery and the coefficient of friction is only 0.3 to 0.6, so the third darkness value switch 343 no longer responds at all.

Therefore, a steep pressure increase does not occur following the constant holding phase. OR gate 372 now no longer receives an L-continuous signal on any of its inputs, but merely receives a clocked signal from astable multipipe layer 355. The twitching, slow pressure increase phase continues throughout the positive half-wave of curve 582 and is completed again only when:
That is, the process is completed only when the dark value falls below the dark value of the fifth dark value switch 340. In the second control cycle, the third memory 3
53 is set again after the first memory 351 is reset.

This memory remains set until the end of the braking process, since on slippery roads the third darkness value switch 343 no longer responds. Therefore, in the second and third control cycles, the control threshold value b is set to the same value as the fifth threshold value. Closing of the inflow valve and opening of the outflow valve therefore take place simultaneously. Looking more closely, it can be seen that the inlet valve is first closed, which means that the input signal of the fifth threshold switch 340 is the first threshold switch 34.
This is because the delay is smaller than that of the input signal No. 1. In the third control cycle, it is assumed that the road is now extremely slippery, such that the coefficient of friction is less than 0.3, and the fourth dark value switch 344 then no longer responds. In this case the brake pressure p is reduced for a much longer time, i.e.
It is lowered to the response of the darkness value switch 342. The switching dark value Q of the second dark value switch 342 has already been adjusted to be sufficiently warm by the third storage device 353 during the second control cycle.
This results in an additional lengthening of the pressure drop phase. When the second function value switch 342 responds, an L signal is applied to the reset input side R of the first memory device 351 via the OR gate 371, and the first memory device 351 is reset, and current no longer flows through the second magnet coil 27. . Up to this point, an L signal is applied to OR gate 372 via AND gate 365. The closing of the outflow valve therefore now takes place simultaneously with the opening of the inflow valve. However, the inlet valve is not kept open continuously, since a steep pressure increase is undesirable on slippery road surfaces.

Since the unstable multipipulator 355 is not blocked, a clock-controlled pressure rise is ensured. Although the operation of the embodiment of FIG. 2 has been described so far, the operation of the speed comparison circuit 347 has not been described.

The speed comparator circuit 347 comes into play in small vehicles, when wheel speeds no longer allow large acceleration values to be determined by pressure control. At high vehicle speeds, the speed comparator circuit 347 is used to prevent the vehicle wheels from being braked to a stop with less deceleration than the threshold. Third
If the first memory 353 has already been set at the same time, the first memory 351 is set by the speed comparison circuit 347 via the AND gate 366 and the OR gate 367. Further, the speed comparison circuit 347 includes the first and second function value switches 34
The threshold value adjustment for 1,342 is performed via the OR gate 363 in the same way as the third storage 353. moreover,
When the speed comparison circuit 347 responds, the first magnet coil 26 is immediately energized via the OR gate 372, and the inflow valve is closed.

Furthermore, after the reaction of the speed comparison circuit 347, the first memory 351 is no longer reset by the fourth dark value switch 344, but by the second value switch 342. The AND gate 361 ensures that the output signal of the first dark value switch 341 is not delivered earlier than the output signal of the second value switch 342, since the corresponding input signals are delayed differently. be.

Therefore, the first memory 351 is set by the first threshold switch 341 only when the second threshold switch 342 also responds at the same time. In the second embodiment of FIG. 3, the first differentiator 430 is also connected to the input terminal 493.

This differentiator is supplied with a DC voltage signal having a magnitude proportional to the circumferential speed of the wheel. The output side of the first differentiator 430 includes a low-pass filter 432 and a second threshold switch 44.
2 are connected. A first function value switch 441 and a second differentiator 435 are connected to the reduced pass filter 432 (which, as in the first embodiment, also preferably has an upper cutoff frequency of 1 bait z). The first function value switch 441 has a switching branch that includes a hysteresis element 454, which is arranged between the output side and the additional input side. On the output side of the second differentiator 435, there are also third and fourth function value switches 443 as in the first embodiment.
, 444 are connected.

The input side of the speed comparison circuit 447 is also connected to the terminals 493 and 494 as in the first embodiment. The output side of the first threshold value switch 441 is connected on the one hand to the set input side S of the second memory 452 and on the other hand to the input side of the OR gate 461.

The reset input R of the second memory 452 is connected to a terminal 495 connected to the brake light switch. The second magnet coil 27 belonging to the outflow valve is controlled by an AND gate 465 with four inputs. Two of these inputs are the second memory 452 and the OR gate 46.
Connected to the output side of 1. Furthermore, and gate 46
The output of 5 is connected via a delay stage 456 to the set input S of the third memory 453 .

The output side of the third function value switch 443 is connected to the reset input side R of the third memory 453 and the astable multipipulator 455.
It is connected to the cut-off input side E of. or gate 463
and ungate 466 are connected as in the first embodiment, in other words the two inputs are each connected to the third
It is connected to the memory 453 and the speed comparison circuit 447. The output side of the AND gate 466 is connected to the second input side of the OR gate 461, while the output side of the OR gate 463 is connected to the threshold adjustment input side of the first threshold switch 441. The input side of the AND gate 462 is the speed comparison circuit 44
7 and the fourth threshold switch 444.

The input side of another AND gate 471 is the second dark value switch 4
42 and the output side of the third storage device 453. The output side of AND gates 462 and 471 is AND gate 46
5 is connected to another input side of 5. The first magnet coil 26 has an OR gate 472 as in the first embodiment.
is connected to the previous calendar.

Two of the input sides of this OR gate are AND gate 4
65 and the speed comparison circuit 447. The third input is connected via an inverting stage 440 to the output of the second threshold switch.The fourth input of the OR gate 472 is connected to the output of the AND gate 464. The two input sides are connected to the output side of the astable multipipulator 455 and the second memory 452.As is clear from the comparison between FIG. 2 and FIG. The fifth function value switch is omitted in the second embodiment and replaced with an inverting stage.In other words, the two changeover values Q and bo are set to the same value of -Shigeru. The first dark value switch 44
1 has a hysteresis element 454 and is therefore also used as a first memory at the same time. A circuit of a threshold switch having a hysteresis element is shown in FIG. The switching hysteresis characteristic produced by hysteresis element 454 is four times.

The output side of the first threshold switch 441 is in the ○ signal state in the rest state. When the wheel acceleration falls below -3.5 mm (deceleration value), the signal changes to L. The wheel acceleration value when this L signal returns to the 0 signal again is not -3.5 degrees, but a value plus 0.5 degrees plus the effective hysteresis characteristic value 4 degrees. Therefore, based on the switching hysteresis characteristic, the output side of the first threshold switch 441 returns to the ○ signal only when the wheel acceleration exceeds +0.5 m. When an L signal is applied to the threshold value adjustment input side of the first threshold value switch 441, the switching value is adjusted, that is, the lower limit value is changed from -3.5 to -2.5.
The upper limit value will be adjusted from 10.5 pm to 11.5 pm. Both the value b3 and the width are 400 y/y as in the first embodiment.
: or 200 evenings/s. Next, the operation of the second embodiment will be explained using FIG. 6.

Curves 982 and 984 correspond to curves 582 and 5 in FIG.
Matches 84.

The pulse diagram in FIG. 6 represents the output voltages of the following stages: the first step value switch 441, the inversion stage 440, the third dark value switch 443, the fourth value switch 444, the third memory 453, and the AND gate. 465 and the output voltage of OR gate 472. Curve 983 of brake pressure p over time is equal to curve 583 in FIG. The steep pressure increase at the start of braking is completed as soon as the pressure falls below the threshold value b2 and ◯ is sent to the output side of the second function value switch 442.

This 0 signal is converted to an L signal by inverting stage 440 so that first magnet coil 26 is controlled via OR gate 472. After a while, the first threshold switch 441 also responds. The L signal on the output side of the threshold switch 441 directly controls the second magnet coil 27 via the OR gate 461 and the AND gate 465, and as a result, the outflow valve is opened. Furthermore, in order to control the second magnet coil 27, it is necessary for the second memory 452 to send out an L signal and the AND gates 471 and 462 to send out a zero signal, but first of all, such a state does not exist. This is because the second memory 452 has already been set and the third memory 453 has not yet been set. Fourth
The output signal of threshold switch 444 is still 0, so that AND gate 462 still outputs a 0 signal. The same applies to the AND gate 471, since the second function value switch 442 still sends out the O signal. In the first control cycle, the pressure reduction phase is terminated when the fourth threshold switch 444 is activated, that is, when the wheel acceleration changes in the positive direction by 200 m/s.

Speed comparator circuit 447 has not responded yet (i.e. 0
), the fourth threshold value switch 44
AND gate 471 by the L signal at the output side of 4
An L signal is also generated on the output side of. As a result, the AND gate 465 no longer sends the L signal to the second magnet coil 27, and the outflow valve is closed again. As a result, the brake pressure p is now held constant. The delay stage 456 is configured as a monostable multipipulator, which is also controlled by the signal change from L to O at the output side of the AND gate 465, and after 2hs sends an L signal at its output side, thereby causing the third storage 453 is set.

The third memory 453 has a dynamic input so that it can only be controlled with a jump signal. The dynamic input side then consists of a series connection of a differential capacitor and a diode. The phase in which the brake pressure p is kept constant continues until the wheel deceleration falls below the threshold value Q again.

When the value falls below this level, the second dark value switch 442 sends out an L signal and the inverting stage 440 sends out a ◯ signal. Therefore, no L signal appears on either of the inputs of OR gate 472 anymore. In the first control cycle, the third threshold switch 443 has also already reacted a short time ago. The input side E is cut off by the L signal on the output side of the third threshold switch 443.
The astable multipipulator 455 is shut off via. Therefore, as described for the third embodiment, a gradual pressure increase is possible. The steep pressure increase continues until the pressure falls below the switching value of the third function switch 443 again.

Since the unstable multipipulator 455 is then no longer blocked, the inlet valve is only clocked via the first magnet coil 26, so that a slow pressure rise continues. This slow pressure increase is terminated at the beginning of the second control cycle, ie when the second threshold switch 442 is again activated and the magnet coil 26 is continuously energized. In short, the second control cycle again begins with a constant hold phase, which lasts only a short time until the first threshold switch 441 responds at a wheel deceleration of -2.5 mm.

That is, the switching value of the first threshold value switch 441 is shifted during this period, because the third memory 453 is placed in the set state some time after the AND gate 465 is switched. The first function value switch 441 opens the outflow valve via the second magnet coil 27, and the brake pressure p quickly decreases. The other opening conditions of the AND gate 465 for pressure reduction are met until the response of the fourth dark value switch 444 as in the first embodiment. The subsequent constant holding phase of the flake pressure p is terminated when the wheel deceleration drops below -2 ta, as in the first control cycle.

In the second control cycle, of course, the road has already become slippery and the third dark value switch 443 is therefore no longer responsive, so that the subsequent pressure increase does not take place quickly but is clock-controlled. This clocked pressure increase accelerates the vehicle wheels until acceleration passes into deceleration due to a linear increase in the braking moment. As soon as the switching threshold value falls below 2, the inflow valve closes and the third
A control cycle is started with a constant brake pressure p phase. The subsequent pressure reduction phase is also initiated by the response of the first threshold switch 441 as in the two first control cycles.

The pressure decrease time phase is also determined by the fourth threshold value switch 444.
It is also not terminated by the threshold switch 442, because firstly the fourth threshold switch 444 no longer responds fully due to the road surface which has become very slippery during that time and secondly the AND gate 471 This is because the entire L signal is no longer sent out. The reason why the above-mentioned state occurs is that the third memory 463 is already in the set state from the first control cycle onward and therefore sends out the L signal. As a result, the pressure drop phase continues until the wheel acceleration increases again to
．． It continues until it increases to the extent that it exceeds the adjusted darkness value b on May 5th. Only when the acceleration increases to such an extent does the first function value switch 441 again send out a 0 signal, and no current flows through the second magnet coil 27. At the same time, no L continuation signal is applied to either input of OR gate 472, resulting in only a clocked pressure increase. As is clear from the three control cycles described above, the duration of the pressure drop phase can be influenced in three stages: on normally dry roads, the fourth threshold switch 444; can be influenced via the AND gate 462; on a slippery road, if the third memory 453 has not yet been set, it can be influenced by the second threshold switch 442: on a slippery road When the third memory 453 is set, the first threshold switch 44
1 can have an influence.

Furthermore, of course, as in the first embodiment, the speed comparison circuit 4
47 can act through a band gate 466. The circuit of the second embodiment shown in FIG. 3 is a speed comparison circuit 44.
7 to very small speed differences, so that at low vehicle speeds the magnet coils 26, 27 can practically only be controlled by the speed comparator circuit 447. Furthermore, the circuit of the hysteresis element and the first dark value switch shown in FIG. 4 will be briefly explained.

The dark value switch 441 has an integrated operational amplifier 480 whose non-inverting input is connected to a resistor 481 and an input terminal 490.
and to the output side of the low-pass filter 432. The inverting input side of the operational amplifier 480 is connected via a resistor 482 to a voltage divider consisting of two resistors 484 and 486 and a variable resistor 485. The output side of operational amplifier 480 is connected to output terminal 491 on the one hand and to positive line 901 via resistor 483 on the other hand. The emitter of the switching transistor 487 is connected to the negative line,
The base is connected to the output side of the operational amplifier 480, and the collector is connected to the tap of a variable resistor 485 via a resistor 488. Further, a resistor 489 is provided between the base of the switching transistor 487 and the negative line 91. The circuit constants of the voltage dividers 484, 485, 486 are dimensioned as follows: in the steady state of the circuit, i.e. when the acceleration is zero, the voltage applied to the input terminal 49 is partially reduced by the switching transistor 487. It is specified to be greater than the tapped voltage of the shorted voltage divider.

The output of the operational amplifier 480 is therefore placed at a positive potential, so that the switching transistor 487 can conduct and the voltage divider can be partially shorted. Therefore, as the output voltage of the differentiator 430 becomes increasingly negative, it falls below the tap voltage of the voltage divider, and the output voltage of the operational amplifier 480 suddenly changes to a negative potential. This causes switching transistor 487 to be cut off; thereby operational amplifier 48
The tapped voltage of the voltage divider 484-486 on the inverting input of 0 becomes significantly higher. Therefore operational amplifier 4
80 is not switched on again at the same voltage value when the voltage at input terminal 490 increases, but only at a much higher voltage value. The threshold switch circuit of FIG. 4 does not yet meet all requirements. That is, when the acceleration is 0, the function value switch must not send out the L signal but send out the O signal. For this purpose, an inverting stage 492 is connected to the operational amplifier 480 , the input of which is connected to the output terminal 491 . In short, the above-mentioned two embodiments of the anti-lock control device solve the problem mentioned at the beginning.

Three different road conditions can be distinguished using the third and fourth threshold switches connected to the front pupil of the second differentiator. In this case, the threshold values for changes in acceleration can be easily adapted to different vehicle types. In the second embodiment, the low-pass filter, memory, and threshold switch are omitted, but operation is not adversely affected in any way. The reliability of the circuit is additionally increased by the provision of different threshold switches for terminating the pressure drop phase for different road conditions: if any one of the threshold switches fails When this occurs, the next dark value switch terminates the pressure drop.

[Brief explanation of drawings]

FIG. 1 shows a diaphragm for explaining the operation of an anti-lock control device having two differentiators connected in series;
Fig. 2 is a block connection diagram of the first embodiment of the present invention, Fig. 3 is a block connection diagram of the second embodiment of the invention, and Fig. 4 is a detailed diagram of an embodiment of a function switch circuit having a hysteresis element. , FIG. 5 is a pulse waveform diagram for explaining the operation of the first embodiment,
FIG. 6 is a pulse waveform diagram for explaining the operation of the second embodiment. 26,27... Magnet coil, 330,430... First differentiator, 332,333,432... Low pass filter, 335,435 Second differentiator, 340-344
, 441-444...function value switch, 347,447
...Speed comparison circuit, 351, 352, 353, 452
,453...Memory device, 355,455...Unstable multipipulator. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 an inlet valve and an outlet valve for electrically controlling the brake pressure, respectively, a rotational speed generator for forming a direct current voltage proportional to the rotational speed of at least one vehicle wheel, and a primary conductor for the time of the wheel speed. A method for controlling an anti-lock control device comprising a circuit arrangement for generating a function and a second derivative, and a threshold switch controlling said valve via a wheel coupling circuit. When a signal corresponding to the second derivative is detected and the first derivative increases following a decrease in brake pressure, a. If the vehicle is traveling on a non-slip road, the signal corresponding to the second derivative is detected. When the signal exceeds a predetermined first threshold value (b_4), the brake pressure is held constant, and in the time phase following the brake pressure constant holding time phase, the signal corresponding to the second derivative is
When the predetermined second threshold value (b_3), which is larger than the threshold value (b_4), is exceeded, the brake pressure is continuously increased, and when it is below the threshold value, the brake pressure is increased stepwise under clock control at a slope slower than the continuous increase slope. b. When the vehicle is traveling on a somewhat slippery road, if the signal corresponding to the second derivative exceeds a predetermined first threshold value (b_4), the brake pressure is held constant and the brake is In the time phase following the constant pressure holding time phase, the signal corresponding to the second derivative is set to a predetermined second threshold value (b_4) larger than the first threshold value (b_4).
b_3) If the brake pressure does not exceed 3), the brake pressure is increased stepwise under clock control at a gradient less than the continuous rise gradient; The signal that
4) and a lock prevention control method characterized in that if the brake pressure is greater than the first threshold value (b_4) and does not exceed a predetermined second threshold value (b_3), the brake pressure is reduced following the brake pressure reduction. .